1. Field of the invention
The present invention relates to fluid flow induced oscillating energy harvesters, particularly to maximizing power output in fluid flow induced oscillating energy harvesters.
2. Background Information
Energy harvesters converting ambient energy into electrical energy have attracted much interest in both the military and commercial sectors. For example, some energy harvesters convert motion of ocean waves into electricity to be used by oceanographic monitoring sensors for autonomous operation. Applications may include high power output devices (or arrays of such devices) deployed at remote locations to serve as reliable power stations. These energy harvesters generally must be sufficiently robust to endure long-term exposure to hostile environments and it is preferable if they have a broad range of dynamic sensitivity to exploit the entire spectrum of wave motions.
Energy harvesters in the form of conventional hydro-electric power generators usually comprise large rotating water turbines requiring extensive civil engineering works, and which require a large pressure head to be effective. This, in turn, historically demanded a high dam for creating the necessary potential energy. These large conventional hydro-electric power generators are not suitable for operating in the shallow waters found in most rivers and tidal flows. As a result, hydroelectric water projects that utilize the entire river flow tend to be quite large thereby consuming large amounts of real estate and capital. The large capital requirements are in addition to the detrimental effects of displacing whole populations of people with wholesale disruption of the local environment and the natural migration of fish.
There are many locations where a large mass of relatively shallow water flows in a constant and reliable manner under a relatively low pressure head, generally in areas of relatively flat terrain, which may not be suitable for efficiently driving a conventional water turbine. Often these locations are conveniently near large inland and some coastal cities, which are the major consumers of electric power. These locations include the fresh water currents in various rivers and streams throughout the world such as, for example, the Mississippi and Amazon Rivers, as well ocean currents such as Gulf Stream and the tidal currents in places like the Bay of Fundy.
Thus, there is a need for a fluid responsive energy harvester which can economically and safely extract useful power from relatively low head shallow waters and to use that power to perform useful work, such as the generation of electricity, nearer the point of consumption, thereby saving the environmentally degradation as well as the capitol expense and losses of power transmission systems.